DESCRIPTION: (Applicant's Description) Current methods for early diagnosis of breast cancer in premenopausal women are not optimal, for reasons related to breast density, tumor growth rates, and potential susceptibility to radiation-induced damage in women with germline predisposing mutations such as BRCA1/2. New methods for early detection in this population that can serve as an adjunct to mammography are urgently needed. We have developed a new approach that can be applied to early detection, based on cytogenetic analysis using comparative genomic hybridization (CGH) of epithelial cells derived from nipple aspirate fluid (NAF). This approach is based on the premise that women with early stages of neoplastic progression will have cytogenetic abnormalities (DNA gains or losses) that can be detected in the cells shed into NAF. In the R21 phase of the proposal we will validate this technique by (1) demonstrating that we can successfully expand NAF-derived cells in culture to produce sufficient DNA for CGH, (2) observe differences in cytogenetic profiles from these cells between women with normal breasts and those with stage I breast cancer (35 women in each group), and (3) that cytogenetic abnormalities detected by CGH in NAF-derived cells from stage I breast cancer patients are consistent with cytogenetic abnormalities detected in tumor tissue from the same patients. In the R33 phase of this research, we will evaluate the translational potential of this approach by further characterizing the pattens of cytogenetic abnormality across stages of neoplastic progression. We will compare CGH profiles in NAF-derived cells from the following four groups of 50 women each: (1) normal women, (2) women with atypical ductal hyperplasia, (3) women with ductal carcinoma in-situ, and (4) women with stage I breast cancer. This will help to determine the stage of neoplastic progression at which early detection based on this approach is feasible.